The present invention relates to improvements to sea platforms for improving the balance of a platform comprising several at least partially submerged columns which are subjected to dynamic effects coming from the sea environment such, for example, as the swell, currents or wind.
In the prior art, such platforms, which are of the semi-submersible type with conventional anchorage or of the type with anchorage by taut lines, comprise columns formed from one or more cylinder portions.
In the case of a column formed of several cylinder portions of differing diameters, the cylinders of larger diameter are situated the deepest, so as to have the submerged volumes required for obtaining the desired buoyancy, while removing the volume from the influence of the swell, currents or winds.
Thus, in the prior art, the section obtained by the intersection of a horizontal plane with the submerged portion of a column is either constant or increases when the depth increases.
The prior art may be illustrated by the British patent application GA-A-2 110 602 which describes columns connected to a point by connecting pieces having a bell shaped form which are not submerged. These connection pieces only play a structural role. Since they are not submerged they do not participate in the hydraulic balancing of the platform. U.S. Pat. No. 1,879,745 also a floating support columns are surrounded by a tubular protective element having an upward diverging shape. This protective element is able to swing in all directions and to move vertically.